As is well-known, mining operations in the past for recovering various metals, e.g., lead, copper, have utilized high grade ore deposits where possible. Many of these deposits have been exhausted and mining of lower grade ores is increasing. The processing of these leaner ores consumes large amounts of time, labor, reagents, power and water with conventional processing.
In addition to the increased expense associated with the extraction of these metals from low grade ores, proposed processes for separation of certain of the sulfide ores are technically very difficult and involve elaborate and expensive equipment. In many cases the expense incurred by such separation would be greater than the commercial value of the metal, such that the mineral recovery, while theoretically possible, is economically unfeasible.
U.S. Pat. No. 4,098,584 "Removal of Impurities from Coal", Ser. No. 767,659, filed Feb. 10, 1977, discloses the cotreatment of coal with a metal containing compound and a gas selected from the group consisting of hydrogen and carbon monoxide in order to selectively enhance the magnetic susceptibility of various impurities contained within the coal. This process selectively enhances both sulfides and various oxides to the exclusion of coal.
Copending patent application "Process for Beneficiating Ores", Ser. No. 921,582 filed July 3, 1978 discloses a method for beneficiating the mineral values of sulfide ores by contacting the ore mixture with an iron carbonyl in order to selectively enhance the magnetic susceptibility of the mineral values. It has been found that this method of beneficiating mineral values can be significantly improved by cotreating the sulfide ores with an iron containing compound and a reducing gas as hereinafter described.